Jimenez won the Hong Kong Open in November last year at the age of 48 years and 318 days, only to break his leg in a skiing accident the following month.
The 49-year-old returned to action in the Spanish Open in April and celebrated his 600th European Tour appearance with a share of fourth place in the BMW PGA Championship a fortnight ago.
And after a top-15 finish in the Nordea Masters last week, Jimenez continued his good form in Austria this morning with four birdies in his first seven holes at Diamond Country Club.
Starting from the 10th, Jimenez birdied his opening hole and also picked up shots on the 12th and 14th before a bogey on the 15th briefly halted his momentum.
A birdie on the 16th took the 49-year-old back to three under par and just one behind Chile's Mark Tullo, who had also started his round on the back nine and birdied the 10th and 11th before making an eagle three on the 13th.
Austrian amateur Matthias Schwab was alongside Jimenez on three under, while home favourite and defending champion Bernd Wiesberger was one under after eight holes.
Former tennis world number one Yevgeny Kafelnikov was already struggling however, the Russian taking six at the par-five 10th and 13th to lie two over par after four holes.
Kafelnikov, 39, has found it difficult to carve out a second career in professional sport, missing the cut here last year by seven shots after rounds of 75 and 77 and by an amazing 27 shots on his debut in the 2008 Russian Open following rounds of 89 and 80.
Jimenez reached the turn in 33 but dropped his second shot of the day on the second to slip back to two under par.
That was two behind joint leaders Schwab and England's Graeme Storm, the former Walker Cup player having recorded a hat-trick of birdies from the seventh to be out in 32.
Schwab, who played in the junior Ryder Cup last year, had covered the back nine in 32 courtesy of birdies at the 10th, 12th, 13th and 16th.
Jimenez saved par after missing the green on the par-three fifth and then birdied the sixth and seventh, both par fives, to improve to four under par.
Playing partner Wiesberger, 61st in the world and seeking to move into the top 60 on Sunday to qualify for next week's US Open, did likewise to also move to four under, but that was still two behind Storm.
Without a win since his sole European Tour victory to date in the 2007 French Open, Storm chipped to two feet on the par-five 13th to card his sixth birdie of the day.